var imagenumber = 17 ;
var randomnumber = Math.random() ;
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ;

images = new Array
images[1] = 'http://www.verticalspirit.ro/images/headers/header01.jpg'
images[2] = 'http://www.verticalspirit.ro/images/headers/header02.jpg'
images[3] = 'http://www.verticalspirit.ro/images/headers/header03.jpg'
images[4] = 'http://www.verticalspirit.ro/images/headers/header04.jpg'
images[5] = 'http://www.verticalspirit.ro/images/headers/header05.jpg'
images[6] = 'http://www.verticalspirit.ro/images/headers/header06.jpg'
images[7] = 'http://www.verticalspirit.ro/images/headers/header07.jpg'
images[8] = 'http://www.verticalspirit.ro/images/headers/header08.jpg'
images[9] = 'http://www.verticalspirit.ro/images/headers/header09.jpg'
images[10] = 'http://www.verticalspirit.ro/images/headers/header10.jpg'
images[11] = 'http://www.verticalspirit.ro/images/headers/header11.jpg'
images[12] = 'http://www.verticalspirit.ro/images/headers/header12.jpg'
images[13] = 'http://www.verticalspirit.ro/images/headers/header13.jpg'
images[14] = 'http://www.verticalspirit.ro/images/headers/header14.jpg'
images[15] = 'http://www.verticalspirit.ro/images/headers/header15.jpg'
images[16] = 'http://www.verticalspirit.ro/images/headers/header16.jpg'
images[17] = 'http://www.verticalspirit.ro/images/headers/header17.jpg'

var image = images[rand1]
document.write("<img src='" +image+ "' alt='Vertical Spirit - sala de escalada' class='float_right'>")